Producing butadiene and derivatives thereof.



UNITED STATES PATENT OFFICE.

OTTO SCHMIDT, OF MANNHEIM, GERMANY, ASSIGNOR T0 BADISCHE ANILIN -& SODA FABRIK, OF LUDWIGSHAFEN-ON-THE-RHINE, GERMANY, A CORPORATION.

PRODUCING BUTADIENE AND DERIVATIVES THEREOF.

1,070,294.. No Drawing.

Specification of Letters Patent.

Patented Aug. 12,1913.

To all whom it may concern:

Be it known that I, O'rro SCHMIDT, subject of the King of Prussia, residing at Mannheim, Germany, have invented new and useful Improvements in Producing Butadiene and Derivatives Thereof, of which the following is a specification.

I have discovered that I can produce 1.3-butadiene and derivatives thereof by suitably heating partially hydrogenized monocyclic hydrocarbons which contain from five to six carbon atoms in the ring and from five to nine carbon atoms in the molecule. Suitable temperatures for carrying out the process of this invention lie between 400 and 800 C. The heating can be carried out either in the presence or absence of indifferent gases and the heat can be applied either externally or internally or both, for instance it can be applied by means of an electrically heated wire, and the heating can be carried out either at ordinary atmospheric pressure or under diminished pressure. It is preferred that the part of the apparatus which is raised to the necessary temperature for the reaction to take place shall be of quartz or platinum or the like and not of an inferior metal, such for instance as iron or nickel. It is preferred to prevent the vaporized hydrocarbons from coming into contact with such inferior metal at a temperature above 100 O. The heat ing should be so carried out that the butadiene or derivative thereof, after its formation, does not remain too long in contact with the heated part of the apparatus. The

- most suitable temperature for the reaction varies with the compound which it is desired to decompose. The temperature should be such that the hydrocarbon employed is sufliciently decomposed and is not obtained to too large an extent in an unaltered condition, while, on the other hand,

the temperature should not be' so high that.

a carbonization of the products takes place; that is to say, the gases leaving the heated tube, or the like, should preferably be white or colorless, and not brown or black. 4

According to the process of the present invention yields of from 60% to 70% of the theoretical possible quantity of butadiene hydrocarbon can easily be obtained. The following examples will serve to illustrate further the nature of my invention,

which, however, is not confined to these ex* amples.

Example 1: Pass a mixture of nitrogen and vaporized A -tetrahydrotoluene through a reaction tube maintained at a dull red heat and cool the escaping gases in steps, so that the unaltered tetrahydrotoluene, which has a higher boiling point, first separates out, and, on further cooling the residual gases, isoprene is condensed.

Instead of diluting the tetrahydrotoluene 1 vapors with nitrogen, they can be passed through the reaction tube at diminished pressure.

Example 2: Pass vapors of tetrahydrobenzene through a tube which is maintained at a red heat and, by fractional cooling, separate the 1.3-butadiene from any unaltered initial material and other products of the reaction. If, in this example, the tetra- GH,.CH=CHCH= on,

It is known that tetrahydrobenzene hydrocarbons can be obtained by heating the corresponding cyclic hexanols at a temperature below 500 0., and consequently this step can be carried out in immediate conjunction with the process of my invention as. de-' scribed in the following example.

Example 3: Pass a mixture of vaporized hexahydro-ortho-cresol and carbon dioxid through a reaction tube filled with pieces of clay and heated so that the inner temperature of the space where the vapors enter is about from 200 to 300 C., and so that the vapors as they pass through the reaction tube are gradually subjected to a higher temperature and finally to a temperature of about 500 0. During the passage, the hexahydro-ortho-cresol is first of all decomposed into tetrahydrotoluene and water, and the former is subsequently converted into isoprene together with some other gaseous compounds. Isolate the isoprene as described in the foregoing Example 1. In this example, the process can be carried out, if desired, at diminished pressure. It is preferred to separate, by means of a suitable condenser, the water formed from the tetrahydrotoluene vapors.

Now what I claim is:

1. The process of producing 1.3-butadiene and derivatives thereof by heating at a temperature between 400 and 800 C. partially hydrogenized monocyclic hydrocarbons which contain from five to six carbon atoms in the ring and from five to nine carbon atoms in the molecule, substantially as hereinbefore described.

2. The process-of producing 1.3-butadiene and derivatives thereof by heating at a temperature between 400 and 800 C. partially hydrogenized monocyclic hydrocarbons which contain from five to six carbon atoms in the ring and from five to nine carbon atoms in the molecule while carrying out the heating under diminished pressure, substantially as hereinbefore described.

3. The process of producing l.3butadiene by heating tetrahydrobenzene at a temperature between 400 and 800 (1., substantially as hereinbefore described.

4. The process of producing 1.3-butadiene by heating tetrahydrobenzene at a temperature between 400 and 800 C. and under diminished pressure substantially as hereinbctore described.

5. The process of producing 1.3-butadiene and derivatives thereof by heating at a temperature between 400 and 800 C. partially hydrogenized monocyclic hydrocarbons which contain from five to siX carbon atoms in the ring and from five to nine carbon atoms in the molecule while preventing the vaporized hydrocarbons from coming into contact with an inferior metal at a temperature above 100 C.

6. The process of producing 1.3-butadiene and derivatives thereof by heating at a temperature between 400 and 800 C. partially hydrogenized monocyclic hydrocarbons which contain from five to six carbon atoms in the ring and from five to nine carbon atoms in the molecule while preventing the,

vaporized hydrocarbons from coming into contact with an inferior metal at a temperature above 100 C., and while carrying out the heating under diminished pressure.

7 The process of producing 1.3butadiene by heating tetrahydrobenzene at a temperature between 400 and 800 C. while preventing the vaporized hydrocarbons from coming into contact with an inferior metal at a temperature above 100 C.

8. The process of producing L3-butadiene by heating tetrahydrobenzene at a temperature between 400 and 800 C. While preventing the vaporized hydrocarbons from coming into contact with an inferior metal at a temperature above 100 C. and while carrying out the heating under diminished pressure.

In testimony whereof I have hereunto set my hand in the presence of two subscribing witnesses.

orro SCHMIDT.

Witnesses:

J. ALEo. LLOYD, Jos. PEIFFER. 

